ANPEP and neoplasm: Liposomes, prepared by the reverse phase method, were made of hydrogenated soy phosphatidylcholine (HSPC), cholesterol (CHE), 1,2-distearoyl-glycero-3-phosphoethanolamine-N-[methoxy(polyethyleneglycol)-2000] (DSPE-PEG2000) and grafted with NGR peptide, able to recognize the specific isoform of aminopeptidase N (APN) (CD13)-positive tumor vasculature.